The Ph.D. viva session was held in the auditorium of the Iranian Fisheries Science and Research Institute for Mr. Masoud Mahjub (admitted for fall 2012) who was the research-based Ph.D. student. The title of his dissertation was "Study on the effects of indigenous probiotics Bacillus subtilis and Bacillus vallismortis on survival, digestive enzymes and the effect of selected probiotic on the gene expression in the immune system of whiteleg shrimp (Litopenaeus vannamei)". The student completed his education in the field of aquatic health at the Shrimp Research Institute of Iran (Bushehr). The doctoral thesis supervisors were Dr. Mirbakhsh and Dr. Afshar Nasab and the doctoral thesis co-supervisors were Dr. Kakulaki and Dr. Saeed Hossein Zadeh. Members of the thesis examination committee were Dr. Sepahdari, Dr. Taheri Mirqhaed and Dr. Hafezieh. The doctoral thesis received a high grade.